Lockjaw Snapper

Wither (This deals damage to creatures in the form of -1/-1 counters.)
When this creature dies, put a -1/-1 counter on each creature with a -1/-1 counter on it.

Serrated Biskelion

{T}: Put a -1/-1 counter on this creature and a -1/-1 counter on target creature.

Tel-Jilad Fallen

Protection from artifacts
Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)

Viridian Betrayers

This creature has infect as long as an opponent is poisoned. (It deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)

Spinebiter

Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)
You may have this creature assign its combat damage as though it weren't blocked.

Melira, Sylvok Outcast

You can't get poison counters.
Creatures you control can't have -1/-1 counters put on them.
Creatures your opponents control lose infect.

Lichenthrope

If damage would be dealt to this creature, put that many -1/-1 counters on it instead.
At the beginning of your upkeep, remove a -1/-1 counter from this creature.

Aerie Ouphes

Sacrifice this creature: It deals damage equal to its power to target creature with flying.
Persist (When this creature dies, if it had no -1/-1 counters on it, return it to the battlefield under its owner's control with a -1/-1 counter on it.)

Witherscale Wurm

Whenever this creature blocks or becomes blocked by a creature, that creature gains wither until end of turn. (It deals damage to creatures in the form of -1/-1 counters.)
Whenever this creature deals damage to an opponent, remove all -1/-1 counters from it.

Urza's Avenger

{0}: This creature gets -1/-1 and gains your choice of banding, flying, first strike, or trample until end of turn. (Any creatures with banding, and up to one without, can attack in a band. Bands are blocked as a group. If any creatures with banding you control are blocking or being blocked by a creature, you divide that creature's combat damage, not its controller, among any of the creatures it's being blocked by or is blocking.)

Aboroth

Cumulative upkeep—Put a -1/-1 counter on this creature. (At the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.)

Cauldron of Souls

{T}: Choose any number of target creatures. Each of those creatures gains persist until end of turn. (When it dies, if it had no -1/-1 counters on it, return it to the battlefield under its owner's control with a -1/-1 counter on it.)

Lesser Masticore

As an additional cost to cast this spell, discard a card.
{4}: This creature deals 1 damage to target creature.
Persist (When this creature dies, if it had no -1/-1 counters on it, return it to the battlefield under its owner's control with a -1/-1 counter on it.)

Crocodile of the Crossing

Haste
When this creature enters, put a -1/-1 counter on target creature you control.

Argivian Avenger

{1}: Until end of turn, this creature gets -1/-1 and gains your choice of flying, vigilance, deathtouch, or haste.

Woodfall Primus

Trample
When this creature enters, destroy target noncreature permanent.
Persist (When this creature dies, if it had no -1/-1 counters on it, return it to the battlefield under its owner's control with a -1/-1 counter on it.)

Contagion Engine

When this artifact enters, put a -1/-1 counter on each creature target player controls.
{4}, {T}: Proliferate twice. (Choose any number of permanents and/or players, then give each another counter of each kind already there. Then do it again.)

Twinblade Slasher

Wither (This deals damage to creatures in the form of -1/-1 counters.)
{1}{G}: This creature gets +2/+2 until end of turn. Activate only once each turn.